Catalysis by canonical radical S-adenosyl-l-methionine (SAM) enzymes involves electron transfer (ET) from [4Fe-4S]+ to SAM, generating an R3S0 radical that undergoes regioselective homolytic reductive cleavage of the S-C5' bond to generate the 5'-dAdo? radical. However, cryogenic photoinduced S-C bond cleavage has regioselectively yielded either 5'-dAdo? or ?CH3, and indeed, each of the three SAM S-C bonds can be regioselectively cleaved in an RS enzyme. This diversity highlights a longstanding central question what controls regioselective homolytic S-C bond cleavage upon SAM reduction? We here provide an unexpected answer, founded on our observation that photoinduced S-C bond cleavage in multiple canonical RS enzymes reveals two enzyme classes in one, photolysis forms 5'-dAdo?, and in another it forms ?CH3. The identity of the cleaved S-C bond correlates with SAM ribose conformation but not with positioning and orientation of the sulfonium center relative to the [4Fe-4S] cluster. We have recognized the reduced-SAM R3S0 radical is a (2E) state with its antibonding unpaired electron in an orbital doublet, which renders R3S0 Jahn-Teller (JT)-active and therefore subject to vibronically induced distortion. Active-site forces induce a JT distortion that localizes the odd electron in a single priority S-C antibond, which undergoes regioselective cleavage. In photolytic cleavage those forces act through control of the ribose conformation and are transmitted to the sulfur via the S-C5' bond, but during catalysis thermally induced conformational changes that enable ET from a cluster iron generate dominant additional forces that specifically select S-C5' for cleavage. This motion also can explain how 5'-dAdo? subsequently forms the organometallic intermediate Ω.Enzymatic deamidation, the conversion of glutamine (Gln) into glutamic acid (Glu) residues, mediated by tissue transglutaminase enzymes, can provoke autoimmunity by generating altered self-epitopes, a process well-known in celiac disease and more recently also described in type 1 diabetes (T1D). To identify deamidated proteins, liquid chromatography-tandem mass spectrometry is the method of choice. However, as nonenzymatic deamidations on asparagine (Asn) and to a minor extent on Gln are frequently induced in vitro during proteomics sample preparation, the accurate detection of in vivo deamidation can be hampered. Here we report on the optimization of a method to reduce in vitro generated deamidation by 70% using improved trypsin digestion conditions (90 min/pH 8). We also point to the critical importance of manual inspection of MS2 spectra, considering that only 55% of the high quality peptides with Gln deamidation were assigned correctly using an automated search algorithm. As proof of principal, using these criteria, we showed a significant increase in levels of both Asn and Gln deamidation in cytokine-exposed murine MIN6 β-cells, paralleled by an increase in tissue transglutaminase activity. These findings add evidence to the hypothesis that deamidation is occurring in stressed β-cell proteins and can be involved in the autoimmune process in T1D.Nanoparticle supercrystals (NPSCs) are of great interest as materials with emergent properties. Different types of intermolecular forces, such as van der Waals interaction and hydrogen bonding, are present in the NPSCs fabricated to date. However, the limited structural stability of such NPSCs that results from the weakness of these intermolecular forces is a challenge. Here, we report a spontaneous formation of NPSCs driven by covalent bonding interactions, a type of intramolecular force much stronger than the above-mentioned intermolecular forces. A model solution-phase anhydride reaction is used to form covalent bonds between molecules grafted on the surface of gold nanoparticles, resulting in three-dimensional NPSCs. The NPSCs are very stable in different solvents, in dried conditions, and at temperatures as high as 160 °C. In addition to this, the large library of covalent-bond-forming reactions available and the low cost of reactants make the covalent bonding approach highly versatile and economical.For the interlayer dielectric in microelectronics, light element compounds are preferably accepted due to less electronic polarization. Here, the nontrivial dielectric nature of the Sb4O6 cage-molecular crystal, known as α-antimony trioxide (α-Sb2O3), is reported. The gas-phase synthesized α-Sb2O3 nanoflakes are of high crystal quality, from which the abnormal local admittance responses were revealed by scanning microwave impedance microscopy (sMIM). https://www.selleckchem.com/products/as1517499.html The remarkably low dielectric constant (k), 2.0?2.5, is corroborated by the analysis of the thickness-dependent sMIM-capacitance signal. In light of the theoretical calculations, the ultralow molecular density and the significantly suppressed ionic polarization are both crucial to the highly reduced k. Combining with the excellent optical band gap, thermal stability, and breakdown strength, α-Sb2O3 is a promising low k dielectric.The sigma 1 receptor (S1R) is a molecular chaperone protein located in the endoplasmic reticulum and plasma membranes and has been shown to play important roles in various pathological disorders including pain and, as recently discovered, COVID-19. Employing structure- and QSAR-based drug design strategies, we rationally designed, synthesized, and biologically evaluated a series of novel triazole-based S1R antagonists. Compound 10 exhibited potent binding affinity for S1R, high selectivity over S2R and 87 other human targets, acceptable in vitro metabolic stability, slow clearance in liver microsomes, and excellent blood-brain barrier permeability in rats. Further in vivo studies in rats showed that 10 exhibited negligible acute toxicity in the rotarod test and statistically significant analgesic effects in the formalin test for acute inflammatory pain and paclitaxel-induced neuropathic pain models during cancer chemotherapy. These encouraging results promote further development of our triazole-based S1R antagonists as novel treatments for pain of different etiologies.